The purpose of this research is to establish the cellular events that follow the cell-mediated antigenic stimulation of immunocompetent cells, the mechanisms of antigenic stimulation, and the genesis of differentiated effector lymphocytes from undifferentiated precursors. The mechanism by which proliferation and differentiation are regulated, and the relaxation between cells synthesizing antibody and the differentiating into cytotoxic effector lymphocytes will be studied. The research will utilize an in vitro culture system in which a primary cell-mediated immune response comparable to that seen in vivo can be obtained, and Cr51 release assay for the enumeration of effector lymphocytes. Cell separation procedures will be utilized for concentrating and separating various cell components involved in this response. Bibliographic references: Lundak, R.L., Kaplan, M.S., and Raidt, D.J. 1975. T Lymphocytes Cell Division: A requirement for the allogeneic cell mediated immune response in vitro. Abstract accepted for presentation at the Surgical Forum, the complete manuscript is in preparation. The abstract is attached.